[linux-lvm] LVM performance

[Steve Wray]

> From: linux-lvm-admin at sistina.com [mailto:linux-lvm-admin at sistina.com]On
> Behalf Of Bradley M Alexander
> On Fri, Nov 23, 2001 at 05:32:07PM +1300, Steve Wray wrote:
> >
> > thats dead right; ide can't simultaneously write to the master and slave
> > on the same controller. Also, the pair of drives uses the controller
> > circuitry
> > of the master, so it always pays to make the master the most modern one.
>
> Since both controllers have a drive master and a cd slave, this shouldn't
> matter, per se.

yeah but I thought I'd mention it, for completeness
:)


> > > Can anyone give me any ideas as to why the machine gets
> beaten about so
> > > much during IO operations and more importantly how can I minimize the
> > > impact.
> >
> > Dunno, if it was because the fs is striped across those drives then
> > splitting them across controllers would have made it go away.
>
> Nothing should be striped across the drives. I have two PVs and made two
> VGs, one on each drive. The way it works out, the data I am
> mastering is on

yup you have to tell it to stripe, as I recall. Never used that feature
tho.

> > I've seen no performance problems at all and really thrashed an LVM-root
> > machine for test purposes while working on a movie. It took it well,
> > performance-wise. (reliability is another issue; never go LVM-root...
> > but thats just my 2 cents, YMMV).
>
> Yeah, I wasn't brave enough to go all out...And with the problems I was
> having, I'm glad I made that decision. :)

I think the worst part is the lack of backward compatibility
at some stages of LVM. With root on LVM it can be a bit dangerous
to upgrade! Or at least it was...